Kuddle Config

An Elixir Config.Provider using kuddle, also general configuration helpers using Kuddle.

Installation

To add kuddle_config to your project:

def deps do
  [
    {:kuddle_config, "~> 0.3.0"}
  ]
end

Usage

Kuddle provides 2 different config providers:

Single File Providers

The default Config.Provider which will load a kdl file as config

Kuddle.Config.Provider

Used for elixir releases:

# Format
defp releases do
  [
    application: [
      config_providers: [
        {Kuddle.Config.Provider, [
          path: config_path()
        ]}
      ]
    ]
  ]
end

# Example
defp releases do
  [
    application: [
      config_providers: [
        {Kuddle.Config.Provider, [
          path: {:system, "PATH_TO_CONFIG", "/default/path/to/kdl/config"}
        ]}
      ]
    ]
  ]
end

Kuddle.Config.Distillery.Provider

Used for distillery releases

# Format
release :my_app do
  set config_providers: [
    {Kuddle.Config.Distillery.Provider, [
      path: config_path()
    ]}
  ]
end

# Example
release :my_app do
  set config_providers: [
    {Kuddle.Config.Distillery.Provider, [
      path: {:system, "PATH_TO_CONFIG", "/default/path/to/kdl/config"}
    ]}
  ]
end

Directory Loaders

Kuddle.Config.DirectoryProvider

# A special config provider that will load every kdl file in a directory as config

# Format
defp releases do
  [
    application: [
      config_providers: [
        {Kuddle.Config.DirectoryProvider, [
          paths: [config_path()],
          extensions: [String.t()]
        ]}
      ]
    ]
  ]
end

# Example
defp releases do
  [
    application: [
      config_providers: [
        {Kuddle.Config.DirectoryProvider, [
          paths: [
            {:system, "PATH_TO_CONFIG", "/default/path/to/kdl/config"}
          ],
          extensions: [".kdl", ".kuddle"]
        ]}
      ]
    ]
  ]
end

Kuddle.Config.Distillery.DirectoryProvider

# Format
release :my_app do
  set config_providers: [
    {Kuddle.Config.Distillery.DirectoryProvider, [
      paths: [config_path()],
      extensions: [String.t()]
    ]}
  ]
end

# Example
release :my_app do
  set config_providers: [
    {Kuddle.Config.Distillery.DirectoryProvider, [
      paths: [
        {:system, "PATH_TO_CONFIG", "/default/path/to/kdl/config"}
      ],
      extensions: [".kdl", ".kuddle"]
    ]}
  ]
end

Other Use Cases

Despite the original purpose of this library being the config providers, the config module itself is quite useful even without the providers:

# Have a KDL blob you wish to load?
{:ok, config} =
  Kuddle.Config.load_config_blob("""
  application {
    node "value"
  }
  """)

[
  application: [
    node: "value"
  ]
] = config

# Have a KDL file you'd like to load?
{:ok, config} = Kuddle.Config.load_config_file("my_kdl_config.kdl")

[
  application: [
    node2: "some_other_value"
  ]
] = config

# Have a directory filled with KDL files you'd like to load into one config?
{:ok, config} = Kuddle.Config.load_config_directory("/my/kdl/configs", [".kdl", ".kuddle"])

[
  data: [
    {MyRepo, [
      database: "database",
      host: "127.0.0.1",
      port: 5432,
    ]},
  ],
  web: [
    http: [
      port: 4000
    ]
  ],
  workers: [
    amqp: [
      host: "127.0.0.1",
      port: 5732,
      virtual_host: "my_workers",
    ]
  ]
] = config

# Have the kuddle document already?
{:ok, config} = Kuddle.Config.load_config_document(document)

[
  logger: [
    console: [
      level: :debug
    ]
  ]
] = config

Config Format

Root nodes are application level config, while subsequent sub nodes will be one level deeper config

application {
  key "value"

  key2 {
    subkey "value"
  }
}

Is equivalent to:

config :application,
  key: "value",
  key2: [
    subkey: "value"
  ]

Config is extracted from both attributes and sub nodes:

application {
  food {
    bacon "1"
    eggs "2"
  }
}

Is equivalent to:

application {
  food bacon="1" eggs="2"
}

Either can be mixed and matched to achieve a comfortable format:

application {
  food bacon="1" {
    eggs "2"
  }
}

There is one tiny gotcha in regards to lists:

application {
  node "value"
}

Would evaluate to:

[
  application: [
    node: "value"
  ]
]

As one would expect, however:

application {
  node "value" "value2"
}

Would evaluate to:

[
  application: [
    node: ["value", "value2"]
  ]
]

Assuming the configuration requires a list, it can be coerced using the (list) annotation on the node:

application {
  (list)node "value"
}

[
  application: [
    node: ["value"]
  ]
]

Sometimes it is useful to set a tuple, which is something most available configuration languages struggle with for elixir:

application {
  (tuple)thing "left" "right"
}

[
  application: [
    thing: {"left", "right"}
  ]
]

You can also cast values into atoms:

logger {
  console {
    level (atom)"debug"
  }
}

[
  logger: [
    console: [
      level: :debug
    ]
  ]
]

A list of all available types and more information can be found in the Kuddle.Config.Types module, or the table below.

Type Annotation	Example
date	start_date (date)"2021-09-14"
utc_datetime	inserted_at (utc_datetime)"2021-09-14T18:00:00.000000Z"
naive_datetime	deleted_at (naive_datetime)"2021-09-14T18:00:00.000000Z"
time	start_time (time)"18:00:23"
decimal	cost (decimal)"0.002500"
atom	level (atom)"debug"
boolean	enable_polling (boolean)"YES"
tuple	(tuple)call_pair "New York" "12003004000"
list	(list)allow_list "117.27.222.122"

Additional types can be registered using kuddle_config :types config:

config :kuddle_config,
  types: [
    geopoint: {MyGeoPoint, :cast},
  ]

defmodule MyGeoPoint do
  def cast(value) do
    {:ok, String.split(value, ",", parts: 2) |> Enum.map(&Decimal.new/1) |> List.to_tuple()}
  end
end

application {
  point (geopoint)"15.27,265.27"
}

[
  application: [
    point: {%Decimal{coef: "1527", exp: -2, sign: 1}, %Decimal{coef: "26527", exp: -2, sign: 1}}
  ]
]